My favourite sports nutrition textbook provides extensive details about factors affecting the absorption of various minerals. One of the most significant of these, for me, is that iron absorption is decreased by tea (including some herbal teas) and coffee. And the one question not answered by the authors is whether or not this applies to decaffeinated tea and coffee to the same extent.
I know there are several people here who have studies sports nutrition. Do any of you know the answer to this? I'm prepared to give up caffeine (but not coffee!) if it would make a difference.